Sermorelin

Sermorelin is GHRH(1-29) amide, the shortest N-terminal fragment of growth hormone-releasing hormone that retains full biological activity. The native hormone is 44 residues; residues 1-29 carry the receptor interaction, and everything beyond is dispensable for activity.

It acts at the GHRH receptor on anterior pituitary somatotrophs, a Gs-coupled receptor signalling through adenylyl cyclase and cyclic AMP to drive both synthesis and release of growth hormone. Because the stimulus enters the axis at its physiological point of control, somatostatin feedback and the pulsatile pattern of secretion are preserved.

That preservation is the mechanistic argument for using a GHRH analog rather than growth hormone itself. Exogenous growth hormone overrides the axis and suppresses endogenous production; a secretagogue works through it. The trade-off is that the response requires functioning somatotrophs, so the compound also serves as a diagnostic probe of pituitary capacity.

Sermorelin is unmodified GHRH(1-29) and is therefore susceptible to dipeptidyl peptidase-4 cleavage, giving it a short plasma half-life. Analogs such as modified GRF(1-29) address this with substitutions at the cleavage site.

Findings below are drawn from published preclinical and clinical work and are presented for research context only.

• Minimal active fragment. Residues 1-29 retain the full biological activity of the 44-residue native hormone.

• Preserved feedback. Acting at the GHRH receptor maintains somatostatin feedback and pulsatile secretion, unlike exogenous growth hormone.

• Diagnostic application. Because a response requires functioning somatotrophs, the compound has been used to assess pituitary growth hormone reserve.

• Short half-life. Unmodified GHRH(1-29) is cleaved by dipeptidyl peptidase-4; this is the limitation that modified analogs were designed to overcome.

• IGF-1 response. Sustained growth hormone and insulin-like growth factor 1 responses to prolonged GHRH-analog stimulation are the endpoints most often reported.

This section describes laboratory handling. It is not clinical guidance, and no safety claim for human or veterinary administration is made or implied.

• Supplied lyophilized. Reconstituted peptide solutions have materially shorter working stability than the dry powder — prepare working aliquots and avoid repeated freeze-thaw cycles.

• Handle as a research chemical of undetermined hazard. Use gloves, eye protection and a laboratory coat.

• Storage temperature and, where applicable, reconstitution conditions are stated on the item specification sheet and the lot Certificate of Analysis, which take precedence over general guidance.

• Dispose of unused material and consumables in accordance with the institutional chemical waste policy.

For laboratory research use only. Not for human or veterinary use. Not a drug, food, cosmetic or dietary supplement.

Sermorelin is GHRH(1-29) amide, the minimal fully active fragment of growth hormone-releasing hormone. It stimulates pituitary growth hormone synthesis and release through the GHRH receptor while preserving somatostatin feedback and pulsatility.

Its short half-life, a consequence of dipeptidyl peptidase-4 cleavage, is the property that motivated the substituted analogs that followed. Available in 5 mg and 10 mg presentations.

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7. Kirk JM, Trainer PJ, Majrowski WH, Murphy J, Savage MO, Besser GM. Treatment with GHRH(1-29)NH2 in children with idiopathic short stature induces a sustained increase in growth velocity. Clin Endocrinol (Oxf). 1994;41(4):487-93.

8. Bueno G, Bueno M, Garagorri JM, Juste G, Rejas J, Alvarez I. Priming with GHRH (1-29) NH2: an aid in differential diagnosis between hypothalamic and pituitary deficiencies. J Pediatr Endocrinol. 1994;7(4):309-16.